A Robinson R44 scenic flight helicopter was likely affected by the rotor wake of a larger helicopter when its pilot encountered control difficulties necessitating a forced landing on the banks of Sydney’s Parramatta River.
On the morning of 7 April 2025, the Bankstown Helicopters-operated R44 took off from Bankstown Airport for a local scenic flight around Sydney Harbour with a pilot and two passengers on board, an ATSB investigation final report details.
About seven minutes into the flight, just as the R44 entered the Parramatta River helicopter lane, a larger EC120 helicopter suddenly appeared about 500–600 ft (150–180 m) in front of it and about 100 ft above them, according to the pilot’s estimate.
The R44 then experienced what the pilot described as very strong turbulence from a vertical motion in the atmosphere.
“In response, the pilot applied full collective to avoid the water, which caused the rotor speed to decay sufficiently for the low rotor speed warning horn to activate,” Acting Director Transport Safety Elaine Hargreaves said.
“The pilot then sighted a suitable forced landing area at Cabarita Park and, using the helicopter’s remaining airspeed and rotor speed, manoeuvred the helicopter to the shoreline for a safe landing.”
Air traffic control primary radar data and the pilot’s report indicated that the R44 had entered the Parramatta River helicopter lane and passed over the Ryde Bridge about 9 seconds behind and slightly below the larger, three-bladed EC120.
“Flight tests have demonstrated helicopter wake turbulence is comparatively larger and less predictable than that of fixed-wing aircraft of comparable weights,” Ms Hargreaves said.
“Helicopter rotor vortices can descend, remain level or climb, and the duration of their persistence can increase significantly in conducive weather conditions.”
Guidance, such as from the United States Helicopter Safety Team, advises helicopter pilots to remain three rotor disks clear of a hovering or taxiing helicopter, and to allow 3 NM and/or 2 minutes for the rotor wake from a preceding helicopter to dissipate.
Read the final report: Wake turbulence encounter and forced landing involving Robinson R44, VH-EWM, about 15 km north-east of Bankstown Airport, New South Wales, on 7 April 2025